It's worth doing this then? Given I'm going to be throwing away 80% of the CSS, I'm curious if there are better libraries I can build on top of. It's always an advantage that you'll be able to easily Google for Bootstrap fixes though.
I'd say go ahead. The nice thing is that you can start with virtually nothing and if you realize later you need really nice widgets, then you can just use those mixins.
Bootstrap is the only framework that looks nice, is responsive, and fully addresses accessibility. The only thing I can fault it for is using Jquery, but I don't use the javascript features, so it doesn't matter (to me) anyway.
